The aim of the project is to identify mechanisms controlling the differential synthesis of normal and abnormal human hemoglobins especially with reference to the thalassemia syndromes, sickle cell anemia and the fetal-adult hemoglobin switch. Two model systems are presently being investigated. One involves the Sendai virus-induced cell fusion of mouse erythroleukemic cells with human fetal liver erythroblasts and human bone marrow erythroid precursors. The other model involves the in vitro culture of human peripheral blood erythroid colony forming units. In both systems it is hoped that factors differentially regulating or influencing Alpha nd Beta globin synthesis can be identified. BIBLIOGRAPHIC REFERENCES: Rieder, R.F. Globin Chain Synthesis in HbD (Punjab)-Beta-Thalassemia. Blood 47. 113. 1976. Rieder, R.F. and James, G.W. III. Translation of Human Globin mRNA: Globin Synthesis in Cells Containing HB Leiden. Blood 47, 489, 1976.